Conventionally, agricultural balers comprise a frame which is travelled on a pair of wheels over a field for picking up therefrom hay, straw or silage grass and feeding such crop material to a baling chamber in which it is compressed to parallelepiped packages under action of a plunger which reciprocates inside the baling chamber. When the packages have reached a predetermined length a tying mechanism is operated to encircle the completed package with a plurality of strands to form a finished bale which will be ejected out of the baler.
As the outlet of the baling chamber is at a substantial height above the field, there is a risk that bales get damaged by their fall from the baling chamber, e.g. because the impact breaks some or all of the strands. Commonly this problem has been solved by providing a guide or slide means at the exit of the baling chamber for reducing the height from which the bale is released onto the field and/or giving a wanted orientation to the bale. In the art such apparatus usually is referred to as “bale chute” or “bale discharge means”.
It has been observed that while manoeuvring on a field, the tail portion constituted by the bale chute is particularly vulnerable to damages caused by collisions with objects on or around the field. In particular the previously deposited bales may form serious obstacles while the baler is driven backwards, e.g. to realign the pick-up to the windrow. When the baler is driven backwards the bale chute may hit the bale on the ground and the impact may seriously deform this chute to the extent that it becomes impossible to use.
Furthermore when an agricultural baler is transported from one place to another, more often than not via public roads, the tail portion of the baler significantly increases the length of the baler. In an attempt to solve this drawback, prior art balers are provided with bale discharge means that are mounted in an extendable manner. This allows the discharge means to be moved between an extended operating position and a retracted transporting position. In a further attempt to facilitate use of such extendable discharge means, the latter can be provided with automatic extending means (for example in the form of an actuator). Via this automatic extending means, the discharge means can be automatically moved between the extended operating position and the retracted transporting position. Such a baler is known from EP 0 974258. The capability of automatically moving the discharge means from one to another position will tend the baler operator to make frequent use of this feature. As a result, the operator will retract the discharge means any time these means are not required for the operation of the baler, thereby driving with retracted discharge means more often. As a result, the frequency of driving the baler with the discharge means in the retracted position significantly increases. For example where a baler with manual discharge means is only driven with retracted discharge means on public roads, an operator might choose to retract the discharge means (automatically) when driving on the field or on a lane.
A drawback of the existing systems is that, where the bale discharge means have been dimensioned to be used in the retracted position when driving on public roads, the discharge means prove to be not strong enough for frequent driving in this retracted position. Particularly when the baler is driven on a field or on a lane (which is typically more uneven than a public road), the discharge means can swing open.
Tests have shown that, when an agricultural baler is driven over an uneven ground surface and when the bale discharge means are in the retracted position, the bale discharge means tend to move out of this retracted position into the extended operating position. In practice, the segments of the bale discharge means will swing open due to the vibrations of the agricultural baler, whereby the swing is further powered by the gravity forces. The swinging forces appear to be larger than the forces that can be born by typically used automatic extending means. In such situation, the automatic extending means fail to keep discharge means in the retracted position, and the discharge means will swing open to the operating position. It will be clear that such a situation is highly dangerous.